Since the invention of the integrated circuit, semiconductor dies have become increasingly more sophisticated and large in size. To ensure providing high quality and reliable products to industry, semiconductor manufactururers traditionally functionally test and optically inspect their integrated circuits before the die is packaged.
Traditionally, to perform functional die testing, off-the-shelf planar probe equipment is implemented to test the functionality of the die. The integrated circuit is usually designed with peripheral testing pads connected to the circuitry and which are accessed by the automated probers. Power is provided to the integrated circuit via the bond pads, and the circuit is dynamically tested for functionality using custom software testing programs. Integrated circuit dies which fail to meet established performance parameters are either identified and repaired, or rejected and never make it to the packaging step. This testing procedure can be rather involved, and may include subjecting the integrated circuit die to vibration, humidity, extreme temperatures, and so forth.
With the advance of the integrated circuit, off-the-shelf automated probers have advanced as well. Automated probers are available from well known companies including Hewlett Packard and Teledyne. Some sophisticated integrated circuits, including digital signal processors, microprocessors, and so forth are known to have die sizes approaching 1" by 1" which is huge by industry standards. As the size of these integrated circuits increasingly become larger, so must the sophistication and conformity of conventional testing equipment.
One interesting technology evolving from Texas Instruments Incorporated of Dallas Tex. is a Spatial Light Modulator (SLM) comprised of a Digital Micromirror Device (DMD). These DMDs can be implemented in both hard copy electrostatic printers, and also used to provide high resolution displays including monitors and large screen televisions. DMDs implemented in the design of a television is disclosed is U.S. Pat. No. 5,079,544, to DeMond et al. entitled Standard Independent Digitized Video System and U.S. Pat. No. 5,061,049 to Hornbeck, entitled Spatial Light Modulator and Method, both assigned to the assignee of the present invention. A DMD incorporated into a hard copy printing device is disclosed in U.S. Pat. No. 5,105,369, to Nelson, entitled Printing System Exposive Module Alignment Method and Apparatus of Manufacture, also assigned to the assignee of the present invention. The teachings of all three of these patents is included herein by reference in the present application.
The development of DMDs for the hard copy printing products is especially challenging due to the fact that the integrated circuits are approaching 5" in length. These DMDs comprise a linear array of micromirrors serving as pixels, and may comprise an array of 64 by 7,056 pixels. One invention which addresses the need to reliably manufacture large integrated circuits of this magnitude is disclosed in the cross referenced patent application, wherein a single reticle is implemented in a step and repeat procedure using conventional photolithography equipment. By implementing a single reticle, the step and repeat procedure exposes the die one module at a time, wherein some intermediate modules are repeated, to reliably align one module with an adjacent module. With this design technique available to fabricate large integrated circuits of enormous sizes, the forgoing invention sets out to provide the testability of an integrated circuit this size and sophistication.